Patent literatures that disclose a method for manufacturing a decorative piece such as an emblem, an applique or a sticker by high frequency dielectric heating, using thermoplastic synthetic resin film as starting material and a decorative piece manufactured by the method include among others Patent Literatures 1, 2 and 3 listed hereinafter.
For instance, a decorative piece as disclosed in Patent Literature 1 includes a lower layer (formed by using vinyl chloride film 11) and an upper layer made of thermoplastic synthetic resin (a polyester sheet 1). A sheet of thermoplastic synthetic resin film may be used as the material of the upper layer. The lower layer may be made of any appropriate material such as woven fabric, knitted fabric, synthetic resin (vinyl chloride 11 in Patent Literature 1) or synthetic leather. When a decorative piece is to be provided as a thermally transferable one, thermal bonding film can be used for the lower layer of the decorative piece.
As described above, a decorative piece having an upper layer that is made of thermoplastic synthetic resin and a lower layer can be manufactured by means of high frequency dielectric heating.
When manufacturing a decorative piece by means of high frequency dielectric heating, a metal mold table that operates as one of the electrodes for high frequency dielectric heating (which corresponds to the lower electrode 16′ in Patent Literature 1) and a carving metal mold that operates as the other electrode for high frequency dielectric heating (which corresponds to the upper electrode 16 in Patent Literature 1) are employed.
A carving metal mold as described above has a fusion cutting blade (which corresponds to the blade section 17 in Patent Document 1) and a pressing blade (which corresponds to the protruding section 14′ in Patent Literature 1). The fusion cutting blade has a sharp edge running along the outer contour line of the pattern to be produced and is employed to cut the thermoplastic synthetic resin film that is the material of the patterned piece to be manufactured by fusion cutting. On the other hand, the edge of the pressing blade is placed in a plane located above the horizontal plane where the sharp edge is found and not as sharp as the above described sharp edge of the fusion cutting blade. The pressing blade is designed to produce a given three-dimensional shape out of the thermoplastic synthetic resin film.
For manufacturing the emblem, if necessary, firstly a pattern is printed on a sheet of thermoplastic synthetic resin film, which is the material of the upper layer. Then, the lower film material is laid on the metal mold table and subsequently a sheet of thermoplastic synthetic resin film, which is the material of the upper layer, is laid thereon. Thereafter, the thermoplastic synthetic resin film and the lower layer material are pressed down from above by means of the carving metal mold and a high frequency dielectric heating operation is executed on them. As a result, the upper layer material is fused and a three-dimensional pattern is formed on the thermoplastic synthetic resin film by the carving operation of the carving metal mold and the pressure applied by the pressing blade. Additionally, the thermoplastic synthetic resin film is fused and cut by the fusion cutting blade to define the outer contour line of the patterned piece.
Furthermore, as a result of the high frequency dielectric heating operation, the thermoplastic synthetic resin film is molten to consequently bond together and unify the upper layer and the lower layer to form a decorative piece. Then, all an unnecessary parts are removed to complete the operation of producing a finished decorative piece.
When the decorative piece to be manufactured is a thermal bonding film type one (in which the lower layer is made of a material having a property like that of thermal adhesives and can thermally be bonded to a jacket or some other outer wear to which it is to be bonded by ironing), a sheet of release paper may be arranged on the lower surface of the formed lower layer. Additionally, transparent carrier film may be arranged on the upper surface of the patterned piece. When the lower layer material is fabric or the like, the lower layer material may be cut by an appropriate known means instead of fusion cutting by high frequency dielectric heating.
As described above, emblems made of thermoplastic synthetic resin can be manufactured at low cost on a mass production basis by means of pressure applied from above and high frequency dielectric heating.